


Needs We Don't Talk About

by Ammeh



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alpha Dimitri Alexandre Blaiddyd, Alpha/Beta/Omega Dynamics, Angst, Being Walked In On, Dimitri tries very hard not to be soft and mostly succeeds, Dissociation, Dom/sub Undertones, F/M, Female My Unit | Byleth, Hallucinations, Hypervigilance, Impregnation, Internalized Social Reproductive Pressures, Intrusive Thoughts, Knotting, Mating Cycles/In Heat, Post-Coital Cuddling, Post-Timeskip | War Phase (Fire Emblem: Three Houses), Post-Traumatic Stress Disorder - PTSD, Pre-Gronder, Under-Negotiated Life-Changing Decisions
Language: English
Status: Completed
Published: 2020-06-22
Updated: 2020-06-22
Packaged: 2021-03-03 20:35:32
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,849
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24851680
Author URL: https://archiveofourown.org/users/Ammeh/pseuds/Ammeh
Summary: Dimitri's in rut, and his body and mind are screaming at him to sire an heir.Byleth's around and willing.It's fine. It's convenient. It doesn't mean anything.
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth
Comments: 36
Kudos: 408
Collections: FE3H Kink Meme





	Needs We Don't Talk About

**Author's Note:**

> Fill for a kink meme request for A/B/O rut with "dark feral Dimitri being horny-mad out of his mind needing to top someone, anyone, immediately!" that got away from me a bit. If you're looking for a fun horny romp, this fic might not be your cup of tea. If you're interested in watching a mating drive duke it out with everything else going on in Dimitri's head, with a large helping of gratuitous porn--you're in the right place.
> 
> To avoid possible confusion since I've seen some headcanons that Dimitri really does see ghosts--the "ghosts" here are intended to be Dimitri's brain voicing internalized social pressures/subconscious thoughts/doubts, not characterizations of the people whose faces they're wearing.

There’s a sweetness, creeping at the edge of his senses, curling into the chinks in his resolve and _distracting_ him. He wants to follow it out of the cathedral and down the bridge, wants to hunt it down and find it and _pin it_.  
  
It’s awakening that base urge that pounds through his veins, the one he remembers from before he tumbled off a cliff and died ( _but not like she did—except she didn’t, did she_ ). But this is stronger than he remembers, a persistent itch that keeps his cock half-plumped in his pants and pulls his traitorous eye hungrily to tits and hips and asses. Mercedes comes in the morning to pray like always, and today her prayers are quiet but her chest is deafening. His mind prowls over how her dress wraps around her tits, how they’d spill free if he stalked over and ripped it open.

Normally he can block out choir practice, ignore the worried or pitying glances sent his way from fools singing hymns to a goddess who isn't fucking _there_ , but today he’s the one looking—at the tight fit of Annette’s dress around her hips, at how Ashe’s trousers frame his rear. Even the choir director crosses his mind as his mind becomes increasingly consumed with the idea of rutting into someone. It’s an annoyance, a distraction. They march in three days and he needs to be focused.

Even when everyone leaves and it's just them again, the assault on his resolve doesn't _stop_. Even when he finally _gives in_ —finds a corner behind the wreckage and fists his cock until he knots his hand, leaves his seed sprayed over the rubble of the cathedral ceiling—some primal snarling part of him still wants something soft and clenching wrapped around his knot, wants to spear someone on his cock until they're flushed and whimpering.

He tries to ignore it. Does up his pants. Puts his codpiece back on. Rips it off a moment later when it pinches his still-plump knot. He'll have time to put it on if there's an attack. It's fine. It'll be fine.

The looser feel of nothing but cloth over his groin somehow makes him even more hyper-aware of the hunger itching at his mind, the phantom scent that wants to pull him away from his mission _._

He can ignore it. He needs to focus.

“Are you going to get yourself killed like a fool before you even continue the Blaiddyd line?” Father snaps from where he’s rolled on the floor, glaring up at him.

“I _died_ for that line,” Glenn hisses.

“You’re going to be useless until you fuck something,” Patricia says disgustedly. “Do you really expect to avenge us while your head is in your cock?”

He remembers enduring through these bouts before, days of sitting twitchy through class, sprinting off to fuck his hand when the bell sounded, trying to work the energy off in the training grounds. They’re right, though. The best way to deal with this is just going to be to find someone to breed.

A village girl? He recalls Sylvain’s many comments on how common girls were desperate to get knocked up with noble bastards, so it shouldn’t be hard to find one willing.

“You're not even going to bother finding someone with a fucking _crest_?” Glenn spits out.

“Dear...” Patricia shakes her head, sighing, “you're going to need all the help you can get if you want to restore the line to something worthwhile. Goddess knows your seed isn't going to add much.”

Father just gives that little huff of air. The disappointed one. The “I thought I raised you better than this” one.

They're right. He should've known better. “I'm sorry. It's just—hard to focus right now.” The urge burning at him doesn't care _who_ , just _what_.

Glenn rolls his eyes ( _too far back, blank and white, Dimitri always hates it when he_ —) “How hard is it to remember the only thing you need to pass on when it's _on the fucking flag_?”

“The next generation can't be the last one, Dimitri,” Father says, sadly. “I thought you would've learned by now what to look for.”

“Right. I remember. Sorry.” Bloodline with an affinity for crests, to make it more likely their children will bear his. Omega, preferably—they get pregnant more easily and are more likely to birth alphas. A beta woman is acceptable.

He remembers all of that, but right now his cock just wants a _hole_.

He rolls the options over in his mind. Possible Imperial sympathies, fathers or brothers who might take offense...they all have drawbacks but he's having trouble caring about any of them right now against the prospect of getting _inside_ someone.

_Tap. Tap._

The professor’s boots echo on the stone behind him—her daily attempt to chat no doubt. Not an omega, but she has a crest. Might be too distracting...he recalls his guilty teenage fascination with her body with clarity. _Stupid thing to waste guilt on_. But he wants to be able to knot someone and forget it, doesn’t know if he can trust his resolve with someone his younger self wanted to fucking _marry_ back before they both fucking _died_.

She stops behind him and something rears in the back of his skull. It’s that fucking smell that’s not a smell, that slight freshness that he just wants to drink into his lungs for no good reason. In an instant his cock goes from a dull throb in his pants to hard and demanding. He remembers desperately trying to hide erections in her presence as a teen, fervently hoping she wouldn’t notice, but now he doesn’t fucking care. Either he can make use of her or it’ll finally scare her off and get her to stop pestering him. He turns around.

Seeing her makes it worse ( _her tits swelling out of her breastplate, her legs exposed so he wouldn’t even have to fumble with skirts to barge between them),_ makes his head scream with the urge to push her to the floor and grind his aching cock against her body.

“We’re meeting in the war room in an hour, if—” she freezes, inhaling deeply. Her pupils dilate. Her tongue darts out to lick lips that still hang slackly open. “You’re...”

“In rut,” he agrees, giving her a last once-over. “You’ll do.”

He doesn’t realize he was expecting her to storm off and leave him alone, until she doesn’t.

She’s staring at the bulge in his trousers. She still hasn’t closed her mouth. That haunting, moreish scent gets stronger, until he almost imagines he can taste it.

Wait.

He grabs her shoulder, shoving his face in the crook of her neck. The smell is heady here, concentrated just below her jaw. He rubs his lips over it, clamps his teeth around the spot where it's strongest and licks as if his tongue is still useful for anything.

Her inhalation is sharp, ragged, hungry. A noise that's almost a mewl vibrates under his lips.

It’s _her_. Everyone knew she was a beta, because no one in their right mind would have their omega daughter join a mercenary band. Omega girls fight with magic if they fight at all. They wear dresses, not pants. He’d thought she was an _alpha_ at first. Had any of them ever _asked_?

“You’re going into heat.” That’s convenient.

“ _Now_ I am,” she grumbles.

“You've been stinking up the whole monastery. You caused this,” he replies, grabbing her arm and pulling her towards the alcove that leads to the Holy Mausoleum. “Fix it.”

“But I’ve been taking...” she trails off, inhaling deeply. “Maybe...my cycle’s off from...”

“I don’t really care about your theories on how this happened,” he snaps, crowding her up against the wall and tugging at the buckles of her breastplate. “Are you going to let me knot you or do I need to find someone else?”

“Oh fuck,” she gasps, throwing her head back. The scent is getting stronger. Her eyes are glazing over. “Yeah.”

Her breastplate comes off in his hands. The crash is too loud when he throws it behind him. He hears pebbles falling. _Whatever_.

Her arms wrap around his neck, her body presses against his front, and he can't feel anything because he's still in armor. He wants to feel her against him but _no_ , the location's too exposed still. He'll be vulnerable enough when he knots her. A guard would be best, but the only alpha he'd have trusted within 30 feet right now is fucking dead, and the rest are too puffed-up on naïve sensibilities to tolerate him breeding the professor without dressing it up in pretty trappings first.

No, finding someone to guard is a bad idea. If he takes her from the front, she could cling to his torso and leave his arms free if someone attacks while they're tied. ( _Heh_. How fortunate that Gustave trained him to fight while encumbered.) The alcove's out of sight...choke point on the approach...easy to hear footsteps...He can afford to take off a glove at least. He can wield a lance without them if necessary. He's done it before.

He eyes her shirt and tights as he loosens the straps on his gauntlet. Flimsy. “Take your clothes off yourself, unless you want to lead your little strategy council wearing nothing but my come.”

She stares for a moment before fumbling at her top. ( _Fuck,_ _her tits_.) She kicks off her boots and shoves her shorts and tights down to her ankles.

He sets his gauntlet on the floor ( _palm up, glove attached, straps ready to tighten_ ) and hooks two fingers into the shaped band still concealing the bottom half of her tits. He yanks down.

A soft groan rises in his throat _._ _Yes._ This is what his mind's been clamoring for. But she's too fucking short. He hunches over, catches the soft flesh of her chest between his teeth and bites down.

“ _Nn!_ ”

He covers her other tit with his bare hand, kneads it, keeps biting and sucking the one he's got his mouth on. When he pulls back it's covered in red marks that scream directly to the part of him craving to _claim_ , to stamp himself into someone and leave something behind.

She parts her legs slightly and he can _hear it_.

Her panties tear under his glove. His cock twitches in his pants as he drinks in the bare curve of her hips, restless to feel them in his hands as he drives into her.

She sucks in a breath. “I can't believe we're doing this,” she mutters.

He snorts. “Out of everything, _this_ is what you have trouble with? Wake up, Professor. I thought you were the practical type.”

She opens her mouth. Closes it. Someone else is screaming in the silence.

He clasps the front of her thigh with his ungloved hand. Thumb between her legs. He can feel a trace of slime smeared on her inner thigh. Her body understands, at least.

The rest of her doesn't. She reaches for the buckles of his chest plate. Before he knows what he's doing, he's grabbed her wrist and pinned it to the wall. ( _Don't squeeze. Don't squeeze.)_

She pushes back against his hold, testing not struggling. He doesn't let her budge and she moans. Her cunt makes another wet noise as her legs shift farther apart.

_So fucking easy._ He slides his hand up until his thumb hits damp curls.

Her hips buck. “I want to see you,” she chokes out, laying her free hand on his armored chest.

“Fine.” He releases her thigh and yanks open the buttons of his trousers. Shoves his underwear down to free his cock and balls. “There.”

“I meant...” she trails off, staring. Her eyes are dazed, pupils blown. “... _Fuck_.”

He shoves two fingers between her legs, to where she's plush and wet like an open wound. She cries out and it inflames the hunger in his veins, the urge telling him to render her lax and pliant and then _mount her_.

He gropes at her soft wet gash until he finds the spot that's yielding, that gives way to a tight little tunnel he can work his fingers up inside.

Her cunt jerks around his fingers, like it's trying to suck them deeper, and he keeps pushing, until his palm's pressed flat against her folds and his fingers are buried up inside her.

She grinds down into his hand, sweet little noises escaping her. ( _He has no idea what he's doing and he wanted to be_ _ **good**_ _for her, wanted to learn—_ ) He shoves away a dead man's fancies with a violent shake of his head. From the mess his hand is becoming, she clearly doesn't require much finesse at the moment.

Her body's melting, weak-kneed, leaning more and more of her weight against the wall. She tilts her head to the side and lets him bite at that spot on her neck as he fucks his fingers up into her. With his greaves on he almost misses when her ankle hooks behind his shin, tugs forward.

He releases her wrist, pulls his fingers out of her cunt, grabs her ass in both hands. She doesn't protest when he steps between her legs, when he lifts her up. Doesn't protest when his cockhead butts up against where she's soft and unprotected.

Her body doesn't want to let him in at first. He strains at her entrance, the flesh of her cunt twitching at the tip of his cock but not _admitting_ him—and then all at once it pops in and he doesn't know if he used too much strength but as long as she's not crying in pain he can't find it in himself to care.

He keeps pressing into her body, digging his cock deeper and deeper to the sound of her overwhelmed gasps. He can't get all the way in like he wants to, part of his cock still hanging out of her body even when it feels like he's hit a barrier, how is he supposed to get his _knot_ in?

Her flesh is squeezing around the part that's stuffed inside her, sucking at it in little jolts. Her mouth's hanging open, is she fucking _coming_?“Oh—fuck— _oh, oh, oh—_ ” Her legs jerk where they're hanging around his hips, her cunt spasms around him, and even more slick gushes out onto his cock.

“Before I'm even all the way in? Focus.” He gives a short jab of his hips. “Figure out how you're taking the rest of this. You don't want _me_ trying to force it.”

Gaze bleary, she rocks in his hands to adjust her weight, testing different angles until he feels her open up around him. She grabs his shoulders and bears down, sinking slowly onto him—“Oh _fuck_ ” she gasps again, and he doesn't wait for her to come this time, pulls her down until his cock is buried to the root and his balls are snug against her ass. She's still twitching around him, panting as she looks up and meets his eye.

He drops his gaze. Focuses on how his prick pulls at her pussy lips as he withdraws, the sheen left on it from being buried up inside her. Watches it get swallowed back up again and again as he starts pumping into her.

Her breasts are bouncing with his thrusts, her abdomen flexed from holding herself upright. The planes of her stomach are so taut and firm that it's hard to imagine it swollen with their chi—his bastard.

His view's interrupted by her hand coming down and rubbing at the juncture of her legs. “ _Di—Dimi_ —”

Something in him flinches, a pang that he doesn't want to dwell on. He hones in on the feeling of plunging into her cunt, the rhythmic flex of their bodies coming together. His knot is starting to expand, stretching her a little wider with each punch of his hips.

He needs to come, needs to put his seed as deep in her as he can and plug her up until it takes. His knot's wide enough now that she whimpers the next time he shoves it in, scrambles after him with her legs trying to keep him there on the outstroke—“You want it? Here,” he hears himself say. He pulls her ass hard towards his groin, crams his cock up tight into her body and _lets go_.

His balls draw up and a shock runs through him. That greedy craving assaulting his mind is roaring triumphantly as he feels his knot swell up inside her and the first thick spurt of come burst out of him, with nowhere to go but deeper.

She's almost sobbing, her fingers clawing at his pauldrons, cunt squeezing tight around him. “Fuck, fuck, _fuck—yes—give—”_

His discipline slips and he looks at her face again. Red, blotchy, wisps of hair stuck to her temples, her eyelashes wet. ( _He's never seen her this unraveled. He made her like this._ ) Their eyes meet accidentally as his cock shoots another pulse of come up into her cunt. She pulls his shoulders down. Her hand cups the back of his neck. Their faces are too close, she's staring right through him, he can't handle—

She leans in. Brushes her lips against his. Another throb runs through him and in the rush of pleasure he can't remember why this is a bad idea, just that _Professor Byleth is kissing him_ and there was a time he wanted this so badly and—he presses back, lets her move her lips against his and stroke her hands over his neck and jaw as he pumps her full.

As his balls release the last few shuddering spurts, the frantic rush starts to fade—in its place a deep, satisfied satiation. He grinds forward lazily for the feel of it but the urgency is gone. That base corner of his brain is telling him he won, he did it, he just needs to defend what he's claimed.

The professor's squished between his chest plate and a stone wall but she doesn't seem to care. She's pressing kisses onto his cheeks and chin. Cuddling up with her face nestled into the exposed sliver of his neck. No one's touched him this affectionately since—

“She doesn't love you,” Patricia says gently. “She's just knot-muddled.”

Right. Of course. This doesn't mean anything. It doesn't need to. This is just another way he can make use of her. A blade to point at his enemies. A hole to sate his lust. A womb to continue the line he's disgraced.

_Monster_.

He lets her burrow into him, stares at the wall. Doesn't know how long it's been when she shifts in his arms and he feels something tug at his knot.

Her cunt.

Because it's inside her.

He fucked the professor. Filled her up with come and tied her. He probably just got her pregnant.

Some part of him is horrified. He's become very skilled at ignoring it.

A distant sound jerks him alert. Footsteps in the cathedral. _One person. Armored. Not trying to be stealthy._ There's a cacophony of conflicting demands in his head— _grab the lance, prepare for an attack_ — _calm down, it's probably nothing_ — _cover her with your body, make sure no one else can come inside her while she smells like this._

He shifts the professor so she's obscured by his body, readies himself to grab his weapon and attack.

“Professor?” someone calls. “Your Highness?”

Sylvain. The part of him preparing for an assassin relaxes minutely, but the part that's rutting tenses, pulls his claim closer to his chest and prepares to fight off a rival. _Not kill. Deter._

“Wait, is somebody in he— _hoooly shit_.” Sylvain rounds the corner and halts in place, wide-eyed. “What are you—“

“Siring an heir,” he says flatly.

“Uh. I see that,” Sylvain says, gaze panning up the legs split around his waist. “Who's the lucky—is that the _professor?_ ”

Byleth's stirring, raises her head with a small confused noise. She jerks in his arms—in the corner of his eye he sees her face go scarlet. Like a puppet being moved by some base drive, he automatically cups the back of her neck and pulls her tighter against him, grinds his knot into her to keep her placid.

“Huh,” Sylvain says, mouth hanging slightly open. “Well, uh...good choice, at least. You could've done a lot worse.” His eyes trace absently over the curves of the professor's naked form pressed up against Dimitri's armor. “Does this mean you're going to marry?”

“We don't have time for pointless sensibilities. I can legitimize it.” Dimitri moves his arm to shield more of her body from view. “Now you can vouch.”

“Gilbert and Lord Rodrigue aren't gonna be happy about this...”

Dimitri snorts. “So they'll claim.”

“You tell them, Sylvain,” Byleth says, muffled into his neck. “Please.”

“I guess you're, uh, not gonna make it to the war council, huh.” He's staring at where Dimitri's hips are flush between her spread thighs. “Unless you want to come too, your Highness—joking!”

He doesn't acknowledge that with a response. He wants to disengage, ignore, but in this state the presence of another alpha is an itch at the back of his spine that he can't tune out. “Go away,” he finally says.

“Got it. I'll go let them know you aren't coming.” With one last lingering look, Sylvain leaves. “Have fun.”

They fall into silence again. The professor's clever enough not to prod at a beast she's leashed to.

She keeps nuzzling at his neck, her lips fluttering over his skin in little brushes that could almost be called kisses. _Knot-muddled. Heat-drunk. It doesn't mean anything._

Thinking about it hurts.

The enticing scent is tapering off. He can feel his knot slowly starting to recede. _You did it. You won._ It doesn't feel like victory. Feels more like coming down to a pile of bodies than he'd ever imagined. This is done. He can't reverse it. He took dominion over another life and changed something and that's the way the world is now.

“Rulership means holding the lives of others in your hands, Dimitri,” Father looks up at him reproachfully. “Why are you balking? I thought you were resolute.”

_I am,_ he thinks. _Please, don't worry._ His hand on Byleth's back involuntarily tightens.

She raises her head, sits upright. Her eyes are staring too deeply, the beast inside him is cringing.

“Are we going to talk about this?” she asks finally.

He shifts his hips, testing the tug of his knot in her cunt. Pulls his cock free. Her cunt gapes for a moment and then contracts, a thick gush of semen that was stoppered up inside her trickling down her ass and onto the floor. He sets her on her feet and bends to pick up his discarded gauntlet.

“No.”

The sound of his boots on the cathedral floor is deafening.

**Author's Note:**

> (...And then they worked it out and confessed feelings and had a lot of pregnant sex before happily raising their baby together; they're still going to end up fine I promise.) I might write something more in this verse, but first I'm taking a break from kink meme fills to get a head start on FE3H Wank Week, which I am extremely hyped for and you should all check out.
> 
> De-anoning on this now, thank you guys so much for the positive reception! ♥


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